You will need a new licence key.
Does this mean I will have to pay for my new version 5.0 license?
Can I ask VMware to provide me with the version 5 license keys as am already having version 4.1 licenses?
No, not if you've got valid support and subscription.
You need to visit the licence portal to upgrade the licence ( I think).
I did this myself last week and I'm pretty sure even though I already had a fully working vCenter 4.1, I was required to input the new v5.0 licence file.
Hey thanks for the information, I checked my VMware license portal after a very long time and to my surprise I had the upgrade options available to a lot of my vmware products including vCenter Server and vSphere Enterprise Plus licenses.
Will be upgrading my infrastructure pretty soon as now I have the licences.